ASMBS Allied Health Nutritional Guidelines for the Surgical Weight Loss Patient
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Surgery for Obesity and Related Diseases 4 (2008) S73-S108
ASMBS Guidelines
ASMBS Allied Health Nutritional Guidelines for the Surgical Weight
Loss Patient
Allied Health Sciences Section Ad Hoc Nutrition Committee:
Linda Aills, R.D. (Chair)a, Jeanne Blankenship, M.S., R.D.b, Cynthia Buffington, Ph.D.c,
Margaret Furtado, M.S., R.D.d, Julie Parrott, M.S., R.D.e,*
a
Private practice, Reston, Virginia
b
University of California, Davis Medical Center, Sacramento, California
c
Florida Hospital Celebration Health, Celebration, Florida
d
Johns Hopkins Bayview Medical Center, Baltimore, Maryland
e
Private practice, Fort Worth, Texas
Received March 11, 2008; accepted March 12, 2008
This document is intended to provide an overview of the nutrition assessment should be conducted preoperatively by
elements that are important to the nutritional care of the a dietitian, physician, and/or well-informed, qualified mul-
bariatric patient. It is not intended to serve as training, a tidisciplinary team to identify the patient’s nutritional and
statement of standardization, or scientific consensus. It educational needs. It is essential to determine any pre-
should be viewed as an educational tool to increase aware- existing nutritional deficiencies, develop appropriate dietary
ness among medical professionals of the potential risk of interventions for correction, and create a plan for postoper-
nutritional deficiencies common to bariatric surgery pa- ative dietary intake that will enhance the likelihood of
tients. success.
The goal of this document is to provide suggestions for The management of postoperative nutrition begins pre-
conducting a nutrition assessment, education, supplementa- operatively with a thorough assessment of nutrient status, a
tion, and follow-up care. These suggestions are not man- strong educational program, and follow-up to reinforce im-
dates and should be treated with common sense. When portant principals associated with long-term weight loss
needed, exceptions should be made according to individual maintenance. A comprehensive nutrition evaluation goes far
variations and the evaluation findings. It is intended to beyond assessing the actual dietary intake of the bariatric
present a reasonable approach to patient nutrition care and patient. It takes into account the whole person, encompass-
at the same time allow for flexibility among individual ing several multidisciplinary facets. Not only should the
practice-based protocols, procedures, and policies. Amend- practitioner review the standard assessment components
ments to this document are anticipated as more research, (i.e., medical co-morbidities, weight history, laboratory val-
scientific evidence, resources, and information become ues, and nutritional intake), it is also important to evaluate
available. other issues that could affect nutrient status, including readi-
ness for change, realistic goal setting, general nutrition
knowledge, as well as behavioral, cultural, psychosocial,
Nutrition care
and economic issues.
The Dietitian’s role is a vital component of the bariatric The role of nutrition education and medical nutrition
surgery process. Nutrition assessment and dietary manage- therapy in bariatric surgery will continue to grow as tools
ment in surgical weight loss have been shown to be an to enhance surgical outcome and long-term weight loss
important correlate with success [1,2]. A comprehensive maintenance are explored further and identified. The fol-
lowing tables suggest the possible components of bariat-
ric nutrition care:
*Reprint requests: American Society for Metabolic and Bariatric Sur-
gery, 100 SW 75th Street, Suite 201, Gainesville, FL 32607. Table 1: Suggested preoperative nutrition assessment
E-mail: info@asmbs.org Table 2: Suggested preoperative nutrition education
1550-7289/08/$ – see front matter © 2008 American Society for Metabolic and Bariatric Surgery. All rights reserved.
doi:10.1016/j.soard.2008.03.002S74 L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108
Table 1
Suggested Preoperative Nutrition Assessment
Recommended Suggested Other considerations
Anthropometrics
Age, sex, race, accurate height and weight, BMI, excess body weight Visual inspection of hair, Waist circumference
skin, and nails Other body measurements
Weight history
Failed weight loss attempts Life events that may have Personal weight loss goals
Recent preoperative weight loss attempt (if required by program) caused weight change
Medical history
Current co-morbidities Past medical history Observation of body fat
Current medications If available: % body fat using distribution
Vitamin/mineral/herbal supplements bioelectrical impedance; Consideration of patients who
Food allergies/intolerances resting metabolic rate are athletic or muscular and
(volume of oxygen uptake); BMI classifications
respiratory quotient
Available laboratory values
Psychological history
History of eating disorder
Current/past psychiatric diagnosis
Other
Alcohol/tobacco/drug use
Problems with eyesight
Problems with dentition
Literacy level
Language barrier
Dietary intake: food/fluid
24-hr recall (weekday/weekend), Cultural diet influences Computerized nutrient analysis
Food frequency record, or Religious diet restrictions (if available)
Food, mood, and activity log (helps identify food group omission or Meal preparation skill level Food preferences
dietary practices that increase nutritional risk) Craving/trigger foods Attitudes toward food
Restaurant meal intake Eats while engaged in other
Disordered eating patterns activities
Physical activity
Physical conditions limiting activity Types of activities enjoyed in Activity preference for the future
Current level of activity the past Attitude toward physical activity
Amount of time spent in
daily sedentary activities
Psychosocial
Motivation/reasons for seeking surgical intervention Confidence to maintain Attitude toward lifestyle change
Readiness to make behavioral, diet, exercise, and lifestyle changes weight loss Attitude toward taking life-long
Previous application of above principles listed to demonstrate ability to Anticipated life changes vitamin supplementation
make lifestyle change Marital status/children
Willingness to comply with program protocol Support system
Emotional connection with food Work schedule
Stress level and coping mechanisms Financial constraints
Identify personal barriers to postoperative success Referral to appropriate
professionals for
specialized physical
activity instruction and/or
mental health evaluation
BMI ⫽ body mass index.L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108 S75
Table 2
Suggested Preoperative Nutrition Education
Recommended Suggested Other considerations
Discuss/include
Importance of taking personal responsibility for self- Realistic goal setting Appropriate monitoring of weight loss
care and lifestyle choices Benefits of physical activity
Techniques for self-monitoring and keeping daily food
journal
Preoperative diet preparation (if required by program)
Postoperative intake Common complaints Long-term maintenance
Adequate hydration Dehydration Self-monitoring
Texture progression Nausea/vomiting Nutrient dense food choices for
Vitamin/mineral supplements Anorexia disease prevention
Protein supplements Effects of ketosis Restaurants
Meal planning and spacing Return of hunger Label reading
Appropriate carbohydrate, protein, and fat intake, and Stomal obstruction from food Healthy cooking techniques
food/fluid choices to maximize safe weight loss, Dumping syndrome Relapse management
nutrient intake, and tolerance Reactive hypoglycemia
Concepts of intuitive eating Constipation
Techniques and tips to maximize food and fluid Diarrhea/steatorrhea
tolerance Flatulence/bowel sounds
Possibility of nutrient malabsorption and importance of Lactose intolerance
supplement compliance Alopecia
Possibility of weight regain
Table 3: Suggested postoperative follow-up mentation, or nutritional complications arising from pre-
Table 4: Suggested biochemical monitoring tools for existing deficiencies. Additional laboratory measures
nutrition status might be required and are defined by the presence of the
Table 5: Suggested postoperative vitamin supplemen- existing individual co-morbid conditions. They are not
tation included in Table 4. Table 4 is a sample of laboratory
measures that programs might consider using to compre-
These suggestions, included in Tables 1-5, have been hensively monitor patients’ nutrition status. It is not a
based on committee consensus and current research that has mandate or guideline for laboratory testing.
documented the pre- and postoperative likelihood of nutri-
tion deficiency [1–18]. Vitamin supplementation (Table 5)
Biochemical monitoring for nutrition status (Table 4) Table 5 is an example of a supplementation regimen.
As advances are made in the field of bariatrics and
Deficiencies of single vitamins are less often encountered nutrition, updates regarding supplementation suggestions
than those of multiple vitamins. Although protein– calorie un- are expected. This information is intended for life-long
dernutrition can result in concurrent vitamin deficiency, most daily supplementation for routine postoperative patients
deficiencies are associated with malabsorption and/or incom- and is not intended to treat deficiencies. Information on
plete digestion related to negligible gastric acid and pepsin, treating deficiencies can be found in the Appendix “Iden-
alcoholism, medications, hemodialysis, total parenteral nutri- tifying and Treating Micronutrient Deficiencies.” A pa-
tion, food faddism, or inborn errors of metabolism. Bariatric tient’s individual co-morbid conditions or changes in
surgery procedures specifically alter the absorption pathways health status might require adjustments to this regimen.
and/or dietary intake. Symptoms of vitamin deficiency are
commonly nonspecific, and physical examination might not be
reliable for early diagnosis without laboratory confirmation. Rationale for recommendations
Most characteristic physical findings are seen late in the course Importance of multivitamin and mineral supplementation
of nutrient deficiency [17].
Laboratory markers are considered imperative for It is common knowledge that a comprehensive bariatric
completing the initial nutrition assessment and follow-up program includes nutritional supplementation guidance,
for surgical weight loss patients. Established baseline routine monitoring of the patient’s physical/mental well-
values are important when trying to distinguish between being, laboratory values, and frequent counseling to rein-
postoperative complications, deficiencies related to sur- force nutrition education, behavior modification, and prin-
gery, noncompliance with recommended nutrient supple- ciples of responsible self-care. As the popularity of surgicalS76 L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108
Table 3
Suggested Postoperative Nutrition Follow-up
Recommended Suggested Other considerations
Anthropometric
Current and accurate height, weight, BMI, and Overall sense of well-being Use of contraception to avoid
percentage of excess body weight pregnancy
Biochemical Activity level Psychosocial
Review laboratory findings when available Amount, type, intensity, and Changing relationship with food
frequency of activity Changes in support system
Stress management
Body image
Medication review
Encourage patients to follow-up with PCP regarding
medications that treat rapidly resolving co-
morbidities (e.g., hypertension, diabetes mellitus)
Vitamin/mineral supplements
Adherence to protocol
Dietary intake
Usual or actual daily intake Estimated caloric intake of usual or Promote anti-obesity foods
Protein intake actual intake containing:
Fluid intake Reinforce intuitive eating style to Omega-3 fatty acids
Assess intake of anti-obesity foods improve food tolerance High fiber
Food texture compliance Appropriate meal planning Lean quality protein sources
Food tolerance issues (e.g., nausea/vomiting, Whole fruits and vegetables
“dumping”) Foods rich in phytochemicals and
Appropriate diet advance antioxidants
Address individual patient complaints Low-fat dairy (calcium)
Address lifestyle and educational needs for long Discourage pro-obesity processed
term weight loss maintenance foods containing:
Refined carbohydrates
Trans and saturated fatty acids
BMI ⫽ body mass index; PCP ⫽ primary care physician.
interventions for morbid obesity continues to grow, concern consume sufficient amounts of unprocessed foods that are
is increasing regarding the long-term effects of nutritional high in vitamins and minerals, such as fruits and vegetables,
deficiencies. Nutritional complications that remain undiag- fish and other protein sources, dairy products, whole grains,
nosed and untreated can lead to adverse health conse- nuts and legumes. Poor dietary selection and habits, coupled
quences and loss of productivity. The benefits of weight loss with the reduced vitamin and mineral content of foods, can
surgery must be balanced against the risk of developing lead to micronutrient deficiencies among the general public
nutritional deficiencies to provide appropriate identification, that interfere with body weight control, increasing the risk
treatment, and prevention. of weight gain and obesity. Therefore, a daily vitamin and
Vitamins and minerals are essential factors and co-fac- mineral supplement is likely to be of value in ensuring
tors in numerous biological processes that regulate body adequate intake of micronutrients for maximal functioning
size. They include appetite, hunger, nutrient absorption, of those processes that help to regulate appropriate body
metabolic rate, fat and sugar metabolism, thyroid and adre-
weight.
nal function, energy storage, glucose homeostasis, neural
Taking daily micronutrient supplements and eating foods
activities, and others. Thus, micronutrient “repletion”
high in vitamins and minerals are important aspects of any
(meaning the body has sufficient amounts of vitamins and
successful weight loss program. For the morbidly obese,
minerals to perform these functions) is not only important
for good health, but also for maximal weight loss success taking vitamin and mineral supplements is essential for
and long-term weight maintenance. appropriate micronutrient repletion both before and after
Obtaining micronutrients from food is the most desirable bariatric surgery. Studies have found that 60 – 80% of mor-
way to ensure the body has sufficient amounts of vitamins bidly obese preoperative candidates have defects in vitamin
and minerals. However, some experts have suggested that D [19 –22]. Such defects would reduce dietary calcium
most individuals in our “fast-paced, eat-out” society fail to absorption and increase a substance known as calcitriol,Table 4
Suggested Biochemical Monitoring Tools for Nutrition Status
Vitamin/mineral Screening Normal range Additional laboratory Critical range Preoperative deficiency Postoperative Comments
indexes deficiency
B1 (thiamin) Serum thiamin 10–64 ng/mL 2RBC transketolase Transketolase activity 15–29%; more common in Rare, but occurs with Serum thiamin responds to
1Pyruvate ⬎20% African Americans and RYGB, AGB, and dietary supplementation
Pyruvate ⬎1 mg/dL Hispanics; often BPD/DS but is poor indicator of
associated with poor total body stores
hydration
B6 (pyridoxine) PLP 5–24 ng/mL RBC glutamic pyruvate PLP ⬍3 ng/mL Unknown Rare Consider with unresolved
L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108
Oxaloacetic anemia; diabetes could
transaminase influence values
B12 (cobalamin) Serum B12 200–1000 pg/mL 1Serum and urinary Serum B12 10–13%; may occur with Common with When symptoms are
MMA ⬍200 pg/mL deficiency older patients and those RYGB in absence present and B12 200–
1Serum tHcy ⬍400 pg/mL taking H2 blockers and of 250 pg/mL, MMA and
suboptimal PPIs supplementation, tHcy are useful; serum
sMMA ⬎0.376 mol/L 12–33% B12 may miss 25–30%
MMA ⬎3.6 mol/ of deficiency cases
mmol CRT
tHcy ⬎13.2 mol/L
Folate RBC folate 280–791 ng/mL Urinary FIGLU RBC folate Uncommon Uncommon Serum folate reflects
Normal serum and ⬍305 nmol/L recent dietary intake
urinary MMA deficiency, rather than folate status;
1Serum tHcy ⬍227 nmol/L anemia RBC folate is a more
sensitive marker
Excessive supplementation
can mask B12 deficiency
in CBC; neurologic
symptoms will persist
Iron Ferritin Males: 2Serum iron Ferritin ⬍20 ng/mL 9–16% of adult women in 20–49% of patients; Low Hgb and Hct are
15–200 ng/mL 1TIBC Serum iron ⬍50 g/dL general population are common with consistent with iron
Females: TIBC ⬎450 g/dL deficient RYGB for deficiency anemia in
12–150 ng/mL menstruating stage 3 or stage 4
women (51%), and anemia; ferritin is an
patients with super acute phase reactant and
obesity (49–52%) will be elevated with
illness and/or
inflammation; oral
contraceptives reduce
blood loss for
menstruating females
Vitamin A Plasma retinol 20–80 g/dL RBP Plasma retinol ⬍10 Uncommon; up to 7% in Common (50%) with Ocular finding may
g/dL some studies BPD/DS after 1 yr, suggest diagnosis
up to 70% at 4 yr;
may occur with
RYGB/AGB
S77S78
Table 4
Continued
Vitamin/mineral Screening Normal range Additional laboratory Critical range Preoperative deficiency Postoperative Comments
indexes deficiency
Vitamin D 25(OH)D 25–40 ng/mL 2Serum phosphorus Serum 25(OH)D ⬍20 Common; 60–70% Common with BPD/ With deficiency, serum
1Alkaline phosphatase ng/mL suggests DS after 1 yr; may calcium may be low or
1Serum PTH deficiency 20–30 ng/ occur with RYGB; normal; serum
2Urinary calcium mL suggests prevalence phosphorus may
insufficiency unknown decrease, serum alkaline
phosphatase increases;
L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108
PTH elevated
Vitamin E Plasma alpha 5–20 g/mL Plasma lipids ⬍5 g/mL Uncommon Uncommon Low plasma alpha
tocopherol tocopherol to plasma
lipids (0.8 mg/g total
lipid) should be used
with hyperlipidemia
Vitamin K PT 10–13 seconds 1DCP 2Plasma Variable Uncommon Common with BPD/ PT is not a sensitive
phylloquinone DS after 1 yr measure of vitamin K
status
Zinc Plasma zinc 60–130 g/dL 2RBC zinc Plasma zinc ⬍70 g/dL Uncommon, but increased Common with BPD/ Monitor albumin levels
risk of low levels DS after 1 yr; may and interpret zinc
associated with obesity occur with RYGB accordingly, albumin is
primary binding protein
for zinc; no reliable
method of determining
zinc status is available;
plasma zinc is method
generally used; studies
cited in this report did
not adequately describe
methods of zinc analysis
Protein Serum albumin 4 – 6 g/dL 2Serum prealbumin Albumin ⬍3.0 g/dL Uncommon Rare, but can occur Half-life for prealbumin is
Serum total 6 – 8 g/dL (transthyretin) Prealbumin ⬍20 mg/dL with RYGB, AGB, 2–4 d and reflects
protein and BPD/DS if changes in nutritional
protein intake is status sooner than
low in total intake albumin, a nonspecific
or indispensable protein carrier with a
amino acids half-life of 22 d
RYGB ⫽ Roux-en-Y gastric bypass; AGB ⫽ adjustable gastric banding; BPD/DS ⫽ biliopancreatic diversion/duodenal switch; PLP ⫽ pyridoxal-5’-phosphate; RBC ⫽ red blood cell; MMA ⫽
methylmalonic acid; tHcy ⫽ total homocysteine; CRT ⫽ creatinine; PPIs ⫽ protein pump inhibitors; FIGLU ⫽ formiminogluatmic acid; CBC ⫽ complete blood count; TIBC ⫽ total iron binding capacity;
Hgb ⫽ hemoglobin; Hct ⫽ hematocrit; RPB ⫽ retinol binding protein; PTH ⫽ parathyroid hormone; 25(OH)D ⫽ 25-hydroxyvitamin D; PT ⫽ prothrombin time; DCP ⫽ des-gamma-carboxypromthrom-
bin.
In general, laboratory values should be reviewed annually or as indicated by clinical presentation. Laboratory normal values vary among laboratory settings and are method dependent. This chart provides
a brief summary of monitoring tools. See the Appendix for additional detail and diagnostic tools.
© Jeanne Blankenship, MS RD. Used with permission.L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108 S79
Table 5
Suggested Postoperative Vitamin Supplementation
Supplement AGB RYGB BPD/DS Comment
Multivitamin-mineral supplement
ⴱA high-potency vitamin containing 100% of daily value for 100% of daily 200% of daily 200% of daily valueⴱ Begin on day 1 after
at least 2/3 of nutrients valueⴱ valueⴱ hospital discharge
Begin with chewable or liquid
Progress to whole tablet/capsule as tolerated
Avoid time-released supplements
Avoid enteric coating
Choose a complete formula with at least 18 mg iron, 400
g folic acid, and containing selenium and zinc in each
serving
Avoid children’s formulas that are incomplete
May improve gastrointestinal tolerance when taken close to
food intake
May separate dosage
Do not mix multivitamin containing iron with calcium
supplement, take at least 2 hr apart
Individual brands should be reviewed for absorption rate and
bioavailability
Specialized bariatric formulations are available
Additional cobalamin (B12)
Available forms include sublingual tablets, liquid drops,
mouth spray, or nasal gel/spray
Intramuscular injection — 1000 g/mo — Begin 0–3 mo after
surgery
Oral tablet (crystalline form) — 350–500 g/d —
Supplementation after AGB and BPD/DS may be required
Additional elemental calcium 1500 mg/d 1500– 2000 mg/d 1800– 2400 mg/d May begin on day 1
Choose a brand that contains calcium citrate and vitamin D3 after hospital
Begin with chewable or liquid discharge or
Progress to whole tablet/capsule as tolerated within 1 mo after
surgery
Split into 500–600 mg doses; be mindful of serving size on
supplement label
Space doses evenly throughout day
Suggest a brand that contains magnesium, especially for
BPD/DS
Do not combine calcium with iron containing supplements:
To maximize absorption
To minimize gastrointestinal intolerance
Wait ⱖ2 h after taking multivitamin or iron supplement
Promote intake of dairy beverages and/or foods that are
significant sources of dietary calcium in addition to
recommended supplements, up to 3 servings daily
Combined dietary and supplemental calcium intake ⬎1700
mg/d may be required to prevent bone loss during rapid
weight loss
Additional elemental iron (above that provided by mvi) — Add a minimum Add a minimum of Begin on day 1 after
Recommended for menstruating women and those at risk of of 18–27 mg/d 18–27 mg/d hospital discharge
anemia (total goal intake ⫽ 50-100 mg elemental iron/d) elemental elemental
Begin with chewable or liquid
Progress to tablet as tolerated
Dosage may need to be adjusted based on biochemical
markers
No enteric coating
Do not mix iron and calcium supplements, take ⱖ2 h apart
Avoid excessive intake of tea due to tannin interaction
Encourage foods rich in heme iron
Vitamin C may enhance absorption of non-heme iron sourcesS80 L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108
Table 5
Continued
Supplement AGB RYGB BPD/DS Comment
Fat-soluble vitamins — — 10,000 IU of vitamin A May begin 2– 4
With all procedures, higher maintenance doses may be weeks after
— — 2000 IU of vitamin D
required for those with a history of deficiency surgery
Water-soluble preparations of fat-soluble vitamins are — — 300 g of vitamin K
available
Retinol sources of vitamin A should be used to calculate
dosage
Most supplements contain a high percentage of beta
carotene which does not contribute to vitamin A toxicity
Intake of 2000 IU Vitamin D3 may be achieved with careful
selection of multivitamin and calcium supplements
No toxic effect known for vitamin K1, phytonadione
(phyloquinone)
Vitamin K requirement varies with dietary sources and
colonic production
Caution with vitamin K supplementation for patients
receiving coagulation therapy
Vitamin E deficiency has been suggested but is not
prevalent in published studies
Optional B complex 1 serving/d 1 serving/d 1 serving/d May begin on day 1
B-50 dosage after hospital
Liquid form is available discharge
Avoid time released tablets
No known risk of toxicity
May provide additional prophylaxis against B-vitamin
deficiencies, including thiamin, especially for BPD/DS
procedures as water-soluble vitamins are absorbed in the
proximal jejunum
Note ⬎1000 mg of supplemental folic acid, provided in
combination with multivitamins, could mask B12
deficiency
Abbreviations as in Table 4.
which, in turn, causes metabolic changes that favor fat which are important for driving many of the biological
accumulation [23–25]. processes that help to regulate body size [29 –31]. As the
Several of the B-complex vitamins, important for appro- rate of noncompliance with prophylactic multivitamin sup-
priate metabolism of carbohydrate and neural functions that plementation increases, the rate of postoperative deficiency
regulate appetite, have been found to be deficient in some may increase almost twofold [32].
patients with morbid obesity [21,26,27]. Iron deficiencies, In the past, it has been thought that the specific nutri-
which would significantly hinder energy use, have been tional deficiencies commonly seen among malabsorptive
reported in nearly 50% of morbidly obese preoperative procedures would not be present in patients choosing a
candidates [21]. Zinc and selenium deficits have been re- purely restrictive surgery such as the adjustable gastric band
ported, as well as deficits in vitamins A, E, and C, all (AGB). However, poor eating behavior, low nutrient-dense
important antioxidants helpful in regulating energy produc- food choices, food intolerance, and a restricted portion size
tion and various other processes of body weight manage- can contribute to potential nutrient deficiencies in these
ment [19,26 –28]. patients as well. Although the incidence of nutritional com-
The risk of micronutrient depletion continues to be quite plications may be less frequent in this patient population, it
high, particularly after surgeries that affect the digestion and would be detrimental to assume that they do not exist.
absorption of nutrients, such as Roux-en-Y gastric bypass It is important for the bariatric patient to take vitamin and
(RYGB) and biliopancreatic diversion with or without du- mineral supplements, not only to prevent adverse health
odenal switch (BPD/DS). RYGB increases the risk of vita- conditions that can arise after surgery, but because some
min B12 and other B vitamin deficits in addition to iron and nutrients such as calcium can enhance weight loss and help
calcium. BPD/DS procedures may also cause an increased prevent weight regain. The nutrient deficiency might be
risk of iron and calcium deficits, along with significant proportional to the length of the absorptive area bypassed
deficiencies in the fat-soluble vitamins A, D, E, and K, during surgical procedures and, to a lesser extent, to theL. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108 S81
percentage of weight lost. Iron, vitamin B12, and vitamin D postoperative changes nor include radioisotope labeling to
deficiencies, along with changes in calcium metabolism, are measure absorption of key nutrients, and the subjects had
common after RYGB. Protein, fat-soluble vitamin, and undergone the procedure for reasons other than weight loss.
other micronutrient deficiencies, as well as altered calcium It is unclear whether intestinal adaptation occurs after
metabolism, are most notably found after BPD/DS. Folate combination procedures and to what degree it affects long-
deficiency has been reported after AGB [33]. Thiamin de- term weight maintenance and nutrition status. Adaptation is
ficiency is common among all surgical patients with fre- a compensatory response that follows an abrupt decrease in
quent vomiting, regardless of the type of procedure per- mucosal surface area and has been well studied in short-
formed. Because many nutritional deficiencies progress bowel patients who require bowel resection [45]. The pro-
with time, patients should be monitored frequently and cess includes both anatomic and functional changes that
regularly to prevent malnutrition [29]. Reinforcement of increase the gut’s digestive and absorptive capacity. Al-
supplement compliance at each patient follow-up is also though these changes begin to take place in the early post-
important in the fight to enhance nutrition status and prevent operative period, total adaptation may take up to three years
nutritional complications. to complete. Adaptation in gastric bypass has not been
considered in absorption or metabolic studies. This consid-
Weight loss and nutrient deficits: restriction eration could be important even when determining early and
versus malabsorption late macro- and micronutrient intake recommendations. The
effect of pancreatic enzyme replacement therapy on vitamin
Malabsorptive procedures such as the BPD/DS are and mineral absorption in this population is also unknown.
thought to cause weight loss primarily through the malab- Purely restrictive procedures such as the AGB can result
sorption of macronutrients, with as much as 25% of protein in micronutrient deficiencies related to changes in dietary
and 72% of fat malabsorbed. Such primary malabsorption intake. It is commonly accepted that because no alteration is
results in concomitant malabsorption of micronutrients made in the absorptive pathway, malabsorption does not
[34,35]. Vitamins and minerals relying on fat metabolism, occur as a result of AGB procedures. However, nutrient
including vitamins D, A, E, K, and zinc, may be affected deficits would be likely to occur because of the low nutrient
when absorption is impaired [36]. The decrease in gastro- intake and avoidance of nutrient-rich foods in the early
intestinal transit time may also result in secondary malab- months postoperatively and later possibly as a result of
sorption of a wide range of micronutrients related to by- excessive band restriction. Food with high nutritional value
passing the duodenum and jejunum or limited contact with such as meat and fibrous fresh fruits and vegetables might
the brush border secondary to a short common limb. Other be poorly tolerated.
micronutrient deficiency concerns reported for patients Literature has been published that addresses the effect of
choosing a procedure with malabsorptive features include malabsorptive, restrictive, and combination surgical proce-
iron, calcium, vitamin B12, and folate. dures on acute and long-term nutritional status. These stud-
Nutrient deficiencies after RYGB can result from either ies have attempted, for the most part, to indirectly determine
primary or secondary malabsorption or from inadequate the surgical impact on nutrition status by the evaluation of
dietary intake. A minimal amount of macronutrient malab- metabolic and laboratory markers. Although some studies
sorption is thought to occur. However, specific micronutri- have included certain aspects of absorption, few have in-
ents appear to be malabsorbed postoperatively and present cluded the necessary components to evaluate absorption of
as deficiencies without adequate vitamin and mineral sup- a prescribed and/or monitored diet in a controlled metabolic
plementation. Retrospective analyses of patients who have setting.
undergone gastric bypass have revealed predictable micro- The following sections examine the pre- and postopera-
nutrient deficiencies, including iron, vitamin B12 and folate tive risks for nutritional deficiencies associated with RYGB,
[26,27–39]. Case reports have also shown that thiamin de- BPD/DS, and AGB. It is important for all members of the
ficiency can develop, especially when persistent postopera- medical team to increase their awareness of the nutritional
tive vomiting occurs [40 – 43]. complications and challenges that lie ahead for the patient.
Few studies that measure absorption after measured and Continued review of current research, by the medical team,
quantified intake have been published. It can be hypothe- regarding advances in nutrition science beyond the bound-
sized that the bypassed duodenum and proximal jejunum aries of the present report cannot be emphasized enough.
negatively affect nutrient assimilation. Bradley et al. [44]
studied patients who had undergone total gastrectomy, the
Thiamin (vitamin B1)
procedure from which the RYGB evolved. The researchers
found that most nutritional status changes in patients were Beriberi is a thiamin deficiency that can affect various
most likely due to changes in intake versus malabsorption. organ systems, including the heart, gastrointestinal tract,
These balance studies were conducted in a controlled re- and peripheral and central nervous systems. Although the
search setting; however, they did not measure pre- and condition is generally considered rare, a number of reported,S82 L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108
and possibly a much greater number of unreported or un- suggested a need for preoperative thiamin testing, as well as
diagnosed cases, of beriberi have occurred among individ- thiamin repletion by diet or supplementation to reduce the
uals who have undergone surgery for morbid obesity. Early risk of “bariatric” beriberi postoperatively.
detection and prompt treatment of thiamin deficits in these
individuals can help to prevent serious health consequences. Postoperative risk. Beriberi has been observed after gastric
If beriberi is misdiagnosed or goes undetected for even a restrictive and malabsorptive procedures. A number of cases
short period, the bariatric patient can develop irreversible of Wernicke-Korsakoff syndrome (WKS), as well as periph-
neuromuscular disorders, permanent defects in learning and eral neuropathy, have been reported for patients having
short-term memory, coma, and even death. Because of the undergone vertical banded gastroplasty [53– 61]. A few
life-altering and potentially life-threatening nature of a thi- incidences of WKS have also been reported after AGB
amin deficiency, it is important that healthcare professionals [43,62,63]. Additionally, reports of thiamin deficiencies and
in the field of bariatric surgery have knowledge of the WKS after RYGB [40,41,64 –73] and several cases of WKS
etiology of the condition, and its signs and symptoms, and neuropathy in patients who had undergone BPD [74]
treatment, and prevention. have been published. Many more cases of WKS are be-
lieved to have occurred with bariatric procedures that have
Etiology of potential deficiency. Thiamin is a water-soluble either not been reported or have been misdiagnosed because
vitamin that is absorbed in the proximal jejunum by an of limited knowledge regarding the signs and symptoms of
active (saturable, high-affinity) transport system [46,47]. In acute or severe thiamin deficits. Because many foods are
the body, thiamin is found in high concentrations in the fortified with thiamin, beriberi has been nearly eradicated
brain, heart, muscle, liver, and kidneys. However, without throughout the world, except for patients with severe alco-
regular and sufficient intake, these tissues become rapidly holism, severe vomiting during pregnancy (hyperemesis
devoid of thiamin [46,47]. The total amount of thiamin in gravidarium), or those malnourished and starved. For this
the body of an adult is approximately 30 mg, with a half-life reason, few healthcare professionals, until recently, have
of only 9 –18 days. Persistent vomiting, a diet deficient in had a patient present with beriberi.
the vitamin, or the body’s excessive utilization of thiamin According to the published reports of thiamin deficits
use can result in a severe state of thiamin depletion within after bariatric procedures, most patients develop such defi-
only a short period, producing symptoms of beriberi ciencies in the early postoperative months after an episode
[46 – 48].
of intractable vomiting. Nausea and vomiting are relatively
Bariatric surgery increases the risk of beriberi through ex-
common after all bariatric procedures early in the postop-
acerbation of pre-existing thiamin deficits, low nutrient intake,
erative period. Thiamin stores in the body are small and
malabsorption, and episodes of nausea and vomiting [49 –51].
maintenance of appropriate thiamin levels requires daily
Chronic or acute thiamin deficiencies in bariatric patients often
replenishment. A deficiency of thiamin for only a couple of
present with symptoms of peripheral neuropathy or Wer-
weeks or less, caused by persistent vomiting, can deplete
nicke’s encephalopathy and Korsakoff’s psychoses [21,48 –
thiamin stores. Symptoms of WKS were reported in a
54]. Early diagnosis of the signs and symptoms of these con-
RYGB patient after only two weeks of persistent vomiting
ditions is extremely important to prevent serious adverse health
[67].
consequences. Even if treatment is initiated, recovery can be
Bariatric beriberi can also develop in postoperative patients
incomplete, with cognitive and/or neuromuscular impairments
who are given infusate containing dextrose without thiamin
persisting long term or permanently.
and other vitamins, which is often the case for patients in
Signs, symptoms, and treatment of deficiency (see critical care units, postoperative patients with complications
Appendix, Table A1) interfering with the ingestion of food, or patients dehydrated
from persistent vomiting. Malnutrition caused by a lack of
Preoperative risk. The risk of the development of beriberi appetite and dietary intake postoperatively also contributes to
after bariatric surgery is far greater for individuals present- bariatric beriberi, as does noncompliance in taking postopera-
ing for surgery with low thiamin levels. Investigators at the tive vitamin supplements.
Cleveland Clinic of Florida reported that 15% of their pre- Although most cases of beriberi occur in the early post-
operative bariatric patients had deficiencies in thiamin be- operative periods, cases of patients with severe thiamin
fore surgery [52]. A study by Flancbaum et al. [21] similarly deficiency more than one year after surgery have been
found that 29% of their preoperative patients had low thia- reported. One study reported WKS in association with al-
min levels. Data obtained by that study also showed a cohol abuse 13 years after RYGB [75]. Other conditions
significant difference between ethnicity and preoperative contributing to late cases of bariatric beriberi include a
thiamin levels. Although only 6.7% of whites presented thiamin-poor diet, a diet high in carbohydrates, anorexia,
with thiamin deficiencies before surgery, nearly one third and bulimia [46 – 48].
(31%) of African Americans and almost one half (47%) of
Hispanics had thiamin deficits. The results of these studies Suggested supplementation. Because of the greater likeli-L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108 S83
hood of low dietary thiamin intake, patients should be sup- tis, resected small bowel, elderly patients) can be impaired,
plemented with thiamin. This is usually accomplished causing an IF deficiency. Subsequent vitamin B12 deficiency
through daily intake of a multivitamin. Most multivitamins (pernicious anemia) occurs without IF production or use,
contain thiamin at 100% of the daily value. Patients having because IF is needed to absorb vitamin B12 in the terminal
episodes of nausea and vomiting and those who are anorec- ileum [77]. Factors that increase the risk of vitamin B12
tic might require sublingual, intramuscular, or intravenous deficiency relevant to bariatric surgery include the follow-
thiamin to avoid depletion of thiamin stores and beriberi. ing:
Caution should be used when infusing bariatric patients
An inability to release protein-bound vitamin B12
with solutions containing dextrose without additional vita-
from food, particularly in hypochlorhydria and
mins and thiamin, because an increase in glucose utilization
atrophic gastritis
without additional thiamin can deplete thiamin stores [76].
Malabsorption due to inadequate IF in pernicious
Thiamin deficiency in bariatric patients is treated with
anemia
thiamin, together with other B-complex vitamins and mag-
Gastrectomy and gastric bypass
nesium, for maximal thiamin absorption and appropriate
Resection or disease of terminal ileum
neurologic function [46 – 48]. Early symptoms of neuropa-
Long-term vegan diet
thy can often be resolved by providing the patient with oral
Medications, such as neomycin, metformin, colch-
thiamin doses of 20 –30 mg/d until symptoms disappear. For
icines, medications used in the management of
more advanced signs of neuropathy or for individuals with
bowel inflammation and gastroesophageal reflux
protracted vomiting, 50 –100 mg/d of intravenous or intra-
and ulcers (e.g., proton pump inhibitors) and anti-
muscular thiamin may be necessary for resolution or im-
convulsant agents [79]
provement of symptoms or for the prevention of such.
Patients with WKS generally require ⱖ100 mg thiamin Cobalamin stores are known to exist for long periods
administered intravenously for several days or longer, fol- (3–5 yr) and are dependent on dietary repletion and daily
lowed by intramuscular thiamin or high oral doses until depletion. However, gastric bypass patients have both a
symptoms have resolved or significantly improved. This can decreased production of stomach acid and a decreased avail-
require months to years. Some patients might have to take ability of IF; thus, a vitamin B12 deficiency could develop
thiamin for life to prevent the reoccurrence of neuropathy. without appropriate supplementation. Because the typical
absorption pathway cannot be relied on, the surgical weight
Vitamin B12 and folate loss patient must rely on passive absorption of B12, which
occurs independent of IF.
Vitamin B12 (cobalamin) and folate (folic acid) are both
involved in the maturation of red blood cells and are com- Signs, symptoms, and treatment of deficiency (see
monly discussed in the literature together. Over time, a Appendix, Table A3)
deficiency in either vitamin B12 or folate can lead to mac-
Preoperative risk. Several medications common to preop-
rocytic anemia, a condition characterized by the production
erative bariatric patients have been noted to affect preoper-
of fewer, but larger, red blood cells and a decreased ability
ative vitamin B12 absorption and stores. Of patients taking
to carry oxygen. Most (95%) cases of megaloblastic anemia
metformin, 10 –30% present with reduced vitamin B12 ab-
(characterized by large, immature, abnormal, undifferenti-
sorption [80]. Additionally, patients with obesity have a
ated red blood cells in bone marrow) are attributed to
high incidence of gastroesophageal reflux disease, for which
vitamin B12 or folate deficiency [77].
they take proton pump inhibitors, thus increasing the poten-
tial to develop a vitamin B12 deficiency.
Vitamin B12
Flancbaum et al. [21] conducted a retrospective study of
Etiology of potential deficiency. RYGB patients have both 379 (320 women and 59 men) pre-operative patients. Vita-
incomplete digestion and release of vitamin B12 from pro- min B12 deficiency was reported as negative in all patients
tein foods. With a significant decrease in hydrochloric acid, of various ethnic backgrounds [21]. No clinical criteria or
pepsinogen is not converted into pepsin, which is necessary symptoms for vitamin B12 deficiency were noted. In the
for the release of vitamin B12 from protein [78]. Because general population, 5–10% present with neurologic symp-
AGB patients have an artificial restriction, yet complete use toms with vitamin B12 levels of 200 – 400 pg/mL. Among
of the stomach, and BPD patients do not have as great a preoperative gastric bypass patients, Madan et al. [27] found
restriction in stomach capacity and parietal cells as RYGB that 13% (n ⫽ 59) of patients were deficient in vitamin B12.
patients, the reduction in hydrochloric acid and subsequent In a comparison of patients presenting for either RYGB or
vitamin B12 deficiency is not as prevalent with these two BPD, Skroubis et al. [81] recently reported that preoperative
procedures. vitamin B12 levels were low-normal in both groups. It
Intrinsic factor (IF) is produced by the parietal cells of would be prudent to screen for, and treat, IF deficiency
the stomach and in certain conditions (e.g., atrophic gastri- and/or vitamin B12 deficiency in all patients preoperatively,S84 L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108
but it is essential for RYGB patients so as not to hasten the some patients may experience extreme delusions, halluci-
development of a potential postoperative deficiency. nations, and, even, overt psychosis [93].
Postoperative risk. Vitamin B12 deficiency has been fre- Suggested supplementation. Because of the frequent lack of
quently reported after RYGB. Schilling et al. [82] estimated symptoms of vitamin B12 deficiency, the suggested dili-
the prevalence of vitamin B12 deficiency to be 12–33%. gence in following up or treating these values among those
Other researchers have suggested a much greater prevalence asymptomatic patients has been questioned. The decision
of B12 deficiency in up to 75% of postoperative RYGB not to supplement or routinely screen patients for B12 defi-
patients; however, most reports have cited approximately ciency should be examined very carefully, given the risk of
35% of postoperative RYGB patients as vitamin B12 defi- irreversible neurologic damage if vitamin B12 goes un-
cient [82– 87]. Brolin et al. [87] reported that low levels of treated for long periods. At least one case report has been
vitamin B12 might be seen as soon as six months after published of an exclusively breastfed infant with vitamin
bariatric surgery, but most often occurring more than one B12 deficiency who was born of an asymptomatic mother
year postoperatively as liver stores become depleted. Sk- who had undergone gastric bypass surgery [94].
roubis et al. [88] predicted that the deficiency will most Deficiency of vitamin B12 is typically defined at levels
likely occur 7 months after RYGB and 7.9 months after ⬍200 pg/mL. However, about 50% of patients with obvious
BPD/DS, although their research did not consider compro- signs and symptoms of deficiency have normal vitamin B12
levels [31]. Kaplan et al. [95] reported that vitamin B12
mised preoperative status and its correlation to postopera-
deficiency usually resolves after several weeks of treatment
tive deficiency. After the first postoperative year, the prev-
with 700 –2000 g/wk. Rhode et al. [96] found that a
alence of vitamin B12 deficiency appears to increase yearly
dosage of 350 – 600 g/d of oral B12 prevented vitamin B12
in RYGB patients [89].
deficiency in 95% of patients and an oral dose of 500 g/d
Although the body’s storage of vitamin B12 is significant
was sufficient to overcome an existing deficiency as re-
(⬃2000 g) compared with daily needs (2.4 g/d), this
ported by Brolin et al. [87] in a similar study. Therefore,
particular deficiency has been found within 1–9 years of supplementation of RYGB patients with 350 –500 g/d may
gastric bypass surgery [29]. Brolin et al. [84] reported that prevent most postoperative vitamin B12 deficiency.
one third of RYGB patients are deficient at four years While most vitamin B12 in normal adults is absorbed in
postoperatively. However, non-surgical variables were not the ileum in the presence of IF, approximately 1% of sup-
explored, and many patients might have had preoperative plemented B12 will be absorbed passively (by diffusion)
values near the lower end of the normal range. Ocon Breton along the entire length of the (non-bypassed) intestine by
et al. [90] compared micronutrient deficiencies among two- surgical weight loss patients given a high-dose oral supple-
year postoperative BPD/DS and RYGB patients and found ment [97]. Thus, the consumption of 350 –500 g yields a
that all nutritional deficiencies were more common among 3.5–5.0-g absorption, which is greater than the daily re-
BPD/DS patients, except for vitamin B12, for which the quirement. Although the use of monthly intramuscular in-
deficiency was more common among the RYGB patients jections or a weekly oral dose of vitamin B12 is common
studied. A lack of B12 deficiency among BPD/DS patients among practices, it relies on patient compliance. Practitio-
might result from a better tolerance of animal proteins in a ners should assess the patient’s preference and the potential
larger pouch, greater pepsin/gastric acid production to re- for compliance when considering a daily, weekly, or
lease protein-bound B12, and increased availability and in- monthly regimen of B12 supplementation. In addition to oral
teraction of IF with the pouch contents. supplements or intramuscular injections, nasal sprays and
Experts have noted the significance of subclinical defi- sublingual sources of vitamin B12 are also available. Pa-
ciency in the low-normal cobalamin range in nongastric tients should be monitored closely for their lifetime, because
bypass patients who do not exhibit clinical evidence of severe anemia can develop with or without supplementation
deficiency. The methylmalonic acid (MMA) assay is the [98].
preferred marker of B12 status because metabolic changes
often precede low B12 levels in the progression to defi- Folate
ciency. Serum B12 assays may miss as much as 25–30% of
Etiology of potential deficiency. Factors that increase the
B12 deficiencies, making them less reliable than the MMA
risk of folic acid deficiency relevant to bariatric surgery
assay [91]. It has been suggested that early signs of vitamin include the following:
B12 deficiency can be detected if the serum levels of both
MMA and homocysteine are measured [91]. Vitamin B12 Inadequate dietary intake
deficiency after RYGB has been associated with megalo- Noncompliance with multivitamin supplementation
blastic anemia [92]. Some vitamin B12-deficient patients Malabsorption
develop significant symptoms, such as polyneuropathy, par- Medications (anticonvulsants, oral contraceptives,
esthesia, and permanent neural impairment. On occasion, and cancer treating agents) [79].L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108 S85
Folic acid stores can be depleted within a few months corrects the deficiency in the vast majority of postoperative
postoperatively unless replenished by a multivitamin supple- bariatric patients [103]. Therefore, persistent folate defi-
ment and dietary sources (i.e., green leafy vegetables, fruits, ciency might indicate a patient’s lack of compliance with
organ meats, liver, dried yeast, and fortified grain products). the prescribed vitamin protocol [32].
It is common knowledge that folic acid deficiency among
Signs, symptoms, and treatment of deficiency (see pregnant women has been associated with a greater risk of
Appendix, Table A4) neural tube defects in newborns. Consistent supplementa-
tion and monitoring among women of child-bearing age,
Preoperative risk. The goals of the 1998 Food and Drug including pre- and postoperative bariatric patients is vital in
Administration policy, requiring all enriched grain products an effort to prevent the possibility of neural tube defects in
to be fortified with folate, included increasing the average the developing fetus.
American diet by 100 g folate daily and decreasing the Because folate does not affect the myelin of nerves,
rate of neural tube defects in childbearing women [99]. neurologic damage is not as common with folate, such as is
Bentley et al. [100] reported that the proportion of women the case for vitamin B12 deficiency. In contrast, patients
aged 15– 44 years old (in the general population) who meet with folate deficiency often present with forgetfulness, irri-
the recommended dietary intake of 400 g/d folate varies tability, hostility, and even paranoid behaviors [29]. Similar
between 23% and 33%. With the increasing popularity of to that evidenced with vitamin B12, most postoperative
high protein/low carbohydrate diets, one cannot assume that RYGB patients who are folate deficient are asymptomatic or
preoperative patients consume dietary sources of folate have subclinical symptoms; therefore, these deficient states
through fortified grain products, fruits, and vegetables. Boy- may not be easily identified.
lan et al. [26] found folate deficiencies preoperatively in
56% of RYGB patients studied. Suggested supplementation. Even though folate absorption
occurs preferentially in the proximal portion of the small
Postoperative risk. Although it has been observed that fo- intestine, it can occur along the entire length of the small bowel
late deficiency after RYGB surgery is less common than B12 with postoperative adaptation. Therefore, it is generally agreed
deficiency and is thought to occur because of decreased that folate deficiency is corrected with 1000 mg/d folic acid
dietary or multivitamin supplement intake, low serum folate [32] and is preventable with supplementation that provides
levels have been cited from 6% to 65% among RYGB 200% of the daily value (800 g). This level can also benefit
patients [26,86,101]. Additionally, folate deficiencies have the fetus in a female patient unaware of her postoperative
occurred postoperatively, even with supplementation. Boy- pregnancy. Folate supplementation ⬎1000 mg/d has not
lan et al. [26] found that 47% (n ⫽ 17) of RYGB patients been recommended because of the potential for masking
had low folate levels six months postoperatively and 41% vitamin B12 deficiency. Carmel et al. [104] suggested that
(n ⫽ 17) had low levels at one year. This deficiency oc- homocysteine is the most sensitive marker of folic acid
curred despite patient adherence to taking a multivitamin status, in conjunction with erythrocyte folate. Although
supplement that contained at least the daily value for folate, folic acid deficiency could potentially occur among post-
400 g [26]. Postoperative bariatric patients with rapid operative bariatric surgery patients, it has not been seen
weight loss might have an increased risk of micronutrient widely in recent studies, especially when patients have
deficiencies. MacLean et al. [86] reported that 65% of been compliant with postoperative multivitamin supple-
postoperative patients had low folate levels. These same mentation. Therefore, it is imperative to closely follow
patients exhibited additional B vitamin deficiencies: 24% folic acid both pre- and postoperatively, especially in
vitamin B12 and 50% thiamin [86]. An increased risk of those patients suspected to be noncompliant with their
deficiency has also been noted among AGB patients, pos- multivitamin supplementation.
sibly because of decreased folate intake. Gasteyger et al.
[33] found a significant decrease in serum folate levels
Iron
(44.1%) between the baseline and 24-month postoperative
measurements. Much of the iron and surgical weight loss research con-
Dixon and O’Brien [101] reported elevated serum ho- ducted to date has been generated from a limited number of
mocysteine levels in patients after bariatric surgery, regard- surgeons and scientists; however, the data have consistently
less of the type of procedure (restrictive or malabsorptive). pointed toward the risk of iron deficiency and anemia after
Elevated homocysteine levels can indicate, not only low bariatric procedures. Iron deficiency is defined as a decrease
folate levels and a greater risk of neural tube defects, but can in the total iron body content. Iron deficiency anemia occurs
also be indicative of an independent risk factor for heart when erythropoiesis is impaired as a result of the lack of
disease and/or oxidative stress in the nonbariatric popula- iron stores. In the absence of anemia, iron deficiency is
tion [102]. However, unlike iron and vitamin B12, the folate usually asymptomatic. Fatigue and a diminished capacity to
contained in the multivitamin supplementation essentially exercise, however, are common symptoms of anemia.S86 L. Aills et al. / Surgery for Obesity and Related Diseases 4 (2008) S73-S108
Etiology of potential deficiency. As with other vitamins and didates have also been found to be iron deficient preopera-
minerals, the possible reasons for iron deficiency related to tively. In one retrospective study of consecutive cases (n ⫽
surgical weight loss are multifactorial and not fully ex- 379), 44% of bariatric surgery candidates were iron defi-
plained in the literature. Iron deficiency can be associated cient [21]. In this report, men were more likely than women
with malabsorptive procedures, combination procedures, to be anemic (40.7% versus 19.1%), as determined by ab-
and AGB, although the etiology of the deficiency is likely to normal hemoglobin values. Women, however, were more
be unique with each procedure. Although the absorption of likely to have abnormal ferritin levels. Anemia and iron
iron can occur throughout the small intestine, it is most deficiency were more common in patients ⬍25 years of age
efficient in the duodenum and proximal jejunum, which is compared with those ⬎60 years of age. Of these, 79% of
bypassed after RYGB, leading to decreased overall absorp- younger patients versus 42% of older patients presented
tion. Important receptors in the apical membrane of the with preoperative iron deficiency, as determined by low
enterocyte, including duodenal cytochrome b are involved serum iron values. Another study found iron levels to be
in the reduction of ferric iron and subsequent transporting of abnormal in 16% of patients, despite a low proportion of
iron into the cell [105]. The effect of bariatric surgery on patients for whom data were available (64%). These studies
these transporters has not been defined, but it is likely that, are in contrast to earlier reports of limited preoperative iron
at least initially, fewer receptors are available to transport deficiency [32,107].
iron. With malabsorptive procedures, there is likely a de-
crease in transit time during which dietary iron has less Postoperative risk. Iron deficiency is common after gastric
contact with the lumen, in addition to the bypass of the bypass surgery, with reports of deficiency ranging from 20% to
duodenum, resulting in decreased absorption. In RYGB 49% [32,98,107,108]. Up to 51% of female patients in one
procedures, decreased absorption is coupled with reduced series were iron deficient, confirming the high-risk nature of
dietary intake of iron-rich foods, such as meats, enriched this population [87]. Among patients with super obesity un-
grains, and vegetables. Those patients who are able to tol- dergoing RYGB with varying limb length, iron deficiency has
erate meat have been shown to have a lower risk of iron been identified in 49 –52% and anemia in 35–74% of subjects
deficiency [38]; however, patient tolerance varies consider- up to 3 years postoperatively [84].
ably and red meat, in particular, is often cited as a poorly In one study, the prevalence of iron deficiency was sim-
tolerated food source. Iron-fortified grain products are often ilar among RYGB and BPD subjects. Skroubis et al. [88]
limited because of the emphasis on protein-rich foods and followed both RYGB and BPD subjects for five years. The
restricted carbohydrate intake. Finally, decreased hydro- ferritin levels at two years were significantly different be-
chloric acid production in the stomach after RYGB [106] tween the two groups, with 38% of RYGB versus 15% of
can affect the reduction of iron from the ferric (Fe3⫹) to the BPD subjects having low levels. The percentage of patients
absorbable ferrous state (Fe2⫹). Notably, vitamin C, found included in the follow-up data decreased considerably in
in both dietary and supplemental sources, can enhance iron both groups and must be taken into account. Although data
absorption of non-heme iron, making it a worthy recom- for 70 RYGB subjects and 60 BPD subjects were recorded
mendation for inclusion in the postoperative diet [39]. at one year, only eight and one subject remained in the
groups, respectively, at five years. It is difficult to comment
on the iron status and other clinical parameters, given the
Signs, symptoms, and treatment of deficiency (see
weight of the data. For example, the investigators reported
Appendix, Table A5)
that 100% of BPD subjects were deficient in hemoglobin,
Preoperative risk. The prevalence of iron deficiency in the iron, and ferritin. However, only one subject remained,
United States is well documented. Premenopausal women making the later results nongeneralizable. Additional stud-
are at increased risk of deficiency because of menstrual ies investigating iron absorption and status are warranted for
losses, especially when oral contraceptives are not used. BPD/DS procedures.
The use of oral contraceptives alone decreases blood loss Menstruating women and adolescents who undergo bariat-
from menstruation by as much as 60% and decreases the ric surgery might require additional iron. One randomized
recommended daily allowance to 11 mg/d (instead of 15 study of premenopausal RYGB women (n ⫽ 56) demonstrated
mg/d) [105]. Women of child-bearing age comprise a large that 320 mg of supplemental oral iron (ferrous sulfate) given
percentage (⬎80%) of the bariatric surgery cases performed twice daily prevented the development of iron deficiency but
each year. The propensity of this population to be at risk of did not protect against the development of anemia [107]. No-
iron deficiency and related anemia is relatively independent tably, those patients who developed anemia were not regularly
of bariatric surgery and, thus, should be evaluated before the taking their iron supplements (ⱖ5 times/wk) during the period
procedure to establish baseline measures of iron status and preceding diagnosis. In that study, a significant correlation was
to treat a deficiency, if indicated. found between the resolution of iron deficiency and adhering to
Women, however, are not the only group at risk of iron the prescribed oral iron supplement regimen. Ferritin levels
deficiency, obese men and younger (⬍25 yr) surgical can- had decreased at two years in the untreated group, but those inYou can also read
